Linked objects with a rotation offset?
This can easily be accomplished with a Copy Rotation constraint.

Create your first object, and Apply location and rotation. Then ALTD to make a linked duplicate. Then, in Object mode, rotate your second object on the Z axis.

Now, add a Copy Rotation constraint to the second object, targetting the first object. The trick is to map the World space of the first object to the Local space of the second object.